With fast development of network technologies, a telecommunication network develops towards integration of a mobile network and a fixed network, so that various telecommunication services are expected to be borne on an IP (Internet protocol) network. However, IP addresses in the IP network are seriously deficient, so that it is impossible to allocate one public network address for each terminal. Therefore, a corresponding private network traversal function needs to be implemented on the IP network, so that a relatively small number of public network IP addresses are used to support a large number of machines in a local area network to access the IP network.
A TURN (Traversal Using Relay NAT, traversal using relay NAT) technology is a technology for implementing private network traversal, where a full name of NAT is Network Address Translation (network address translation). In the existing TURN technology, a communications terminal in a local area network sends signaling and communication data used to implement communication with a remote node to a TURN server located in a public network through a TCP protocol or UDP protocol, for example, the communications terminal sends a resource allocate request Allocate request to the TURN server through the TCP protocol (Transmission Control Protocol, transmission control protocol) or the UDP protocol (User Datagram Protocol, user datagram protocol, so as to request the TURN server to allocate a relay address, a resource port, and other communication resources used to communicate with the remote node, and sends a data packet used to communicate with the remote node to the TURN server through the TCP or UDP protocol, and the TURN server relays the data packet to the remote node by using the relay address and the resource port. The communications terminal sends signaling and communication data used to communicate with different remote nodes to different ports of the TURN server, so as to implement communication with the different remote nodes through the different ports of the TURN server.
Usually, a firewall or a proxy server is also deployed between the local area network and the public network, so that the local area network is prevented from being intruded by unauthorized users. Under an environment such as a hotel, an airport, or a prison, a firewall only opening an HTTP port (for example, an HTTP default port 80/433 port) and only allowing a data packet with an HTTP format to pass through is often deployed, the message and the communication data used to implement communication with the remote node may be blocked by the firewall or the proxy server, so that communication between the communications terminal in the local area network and the remote node cannot be implemented.